Chemical-mechanical polishing (“CMP”) is a commonly used technique for planarizing material on a semiconductor wafer. CMP often requires introduction of a polishing slurry as the wafer is being mechanically polished against a rotating polishing pad. Slurries typically are water based and can contain fine abrasive particles such as silica, alumina, and other abrasive materials. After CMP is complete, the wafers are exposed to cleaning chemistries to remove residual slurry and other residue in order to prepare the wafer for subsequent fabrication utilizing techniques such as etching, photolithography, ion-implantation and the like.
Cleaning chemistries may be delivered to the post-CMP wafer cleaner directly from a bulk supply of a particular fabrication facility. However, the flow of cleaning chemistry from the bulk supply may vary depending upon demands placed upon the bulk supply by other post-CMP cleaning systems.
Therefore, liquid delivery modules having a cleaning chemistry storage capacity are frequently employed to dispense cleaning chemistry for post-CMP wafer cleaning. This configuration renders the flow of cleaning chemistry to the post-CMP cleaning tool essentially independent of the flow of cleaning chemistry from the bulk supply.
Because of the need for rapid throughput of polished wafers to be cleaned, it is desirable that the liquid delivery module provide a continuous flow of cleaning chemistry, interrupted only by the transfer of a cleaned wafer out of the cleaner and the loading of the next wafer to be cleaned. In addition, due to space considerations and the need for ease of servicing, it is desirable that the liquid delivery module occupy as little space as possible, and also that the design of the liquid delivery module be relatively simple to permit ready access to various components of the device. Accordingly, new compact and simple designs for liquid delivery modules to dispense fluids utilized in semiconductor fabrication process are desirable.
It is also sometimes desirable that two different chemicals be selectively mixed and/or delivered to respective sides of a wafer.